The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
At present, the 3G network (The Third Generation Network) is gradually evolving into a full IP network. Not only network entities supporting IP are used in the core network and IP based techniques are used in the access network, terminals also become IP clients that may be activated. In the 3G network, a terminal may move in home network, or roam to a network of other operators. No matter whether the terminal roams, when the terminal accesses a network and uses the services provided by the operator, the network side will execute a strict AAA (Authentication, Authorization and Accounting) procedure to the terminal, i.e. authenticating the terminal accessed first, and verifying the validity of the terminal identity; authorizing the terminal appropriate right according to the type of the service applied by the terminal after the authentication is completed; and finally charging according to the resources occupied by the terminal.
FIG. 1 is a conventional flowchart illustrating the process of transferring a session establishment request. Referring to FIG. 1, suppose that there is one intermediate network between a visited network of a terminal and a home network of the terminal, in the related art, when the terminal roams and needs to establish a session connection, the process of transferring the session establishment request by network nodes is implemented by randomly selecting AAA proxy servers of the networks, which comprises the following steps:
Step 101: an AAA client in a WLAN (Wireless local network) access network of the visited network of a terminal receives a session establishment request sent from the terminal.
Step 102: the AAA client randomly selects a first AAA proxy server from the AAA servers of the visited network, and sends the session establishment request to the first AAA proxy server.
Step 103: the first AAA proxy server selects a second AAA proxy server from the AAA servers of the intermediate network, and sends the session establishment request to the second AAA proxy server.
Step 104: the second AAA proxy server selects a destination AAA server from the AAA servers of the home network of the terminal, and sends the session establishment request to the destination AAA server.
After a session connection is established via the above process as shown in FIG. 1, if the terminal initiates other related requests of this session, such as a session termination request, in the WLAN access network of the visited network during the session or at the end of the session, network nodes will send the session termination request to the destination AAA server of the home network of the terminal by randomly selecting AAA proxy servers as well. That is, the AAA client of the visited network selects a third AAA proxy server from the AAA servers of the visited network, and sends the session establishment request to the third AAA proxy server; the third AAA proxy server selects a fourth AAA proxy server from the AAA servers of the intermediate network, and sends the session establishment request to the fourth AAA proxy server; the fourth proxy server sends the session termination request to the destination AAA server.
It can be seen from the above descriptions, in the related art, if a terminal roams, the network side needs to randomly select AAA proxy servers of the network for transferring each session request of the same session of the terminal. For example, for each session request, the AAA client needs to randomly select an AAA proxy server of the visited network of the terminal; the selected AAA proxy server also needs to randomly select an AAA proxy server of the intermediate network. In this way, it can not be ensured that all the session requests related to one session are transferred via the same AAA proxy servers. For example, in the aforesaid process, the session establishment request is transferred by the first AAA proxy server of the visited network and the second proxy server of the intermediate network; the subsequent session termination request, however, is transferred by the third AAA proxy server of the visited network and the fourth AAA proxy server of the intermediate network. The first and third AAA proxy servers as well as the second and fourth AAA proxy servers are usually not the same. Thus, in the related art, different AAA proxy servers are used to transfer different session requests of the same session.
The inventor of the present invention found in the inventing process that, since an AAA proxy server needs to constantly modify the session state maintained by the AAA proxy server according to the received session request, if different AAA proxy servers are used for transferring different session requests of the same session, each AAA proxy server will be unable to maintain a correct session state, which may cause a series of problems such as errors in charging and errors in IP access control. For example, in the visited network, the first AAA proxy server is selected for transferring the session establishment request, and the first AAA proxy server will create the session correspondingly. However, for the session termination request transfer, the third AAA proxy server of the network is used. Since the session termination request is not transferred by the first proxy server, the first AAA proxy server may not obtain the information on the session termination, and thus will not convert the state of the session into termination and will not end the processing of the created session, which may cause a series of problems such as errors in charging and errors in IP access control.